MIAMI — A groundball to third base was, for years, the surest thing the Washington Nationals could count on. It put the game in the steady grip of Ryan Zimmerman — their best player, their Gold Glover, their rock. Zimmerman may still deliver the spectacular, and by virtue of his contributions and contract, he remains a foundational piece of the franchise. But when the ball bounds toward him now, certainty no longer travels with it.

A team with no major perceived weaknesses entering the season, the Nationals now have one major question in the form of Zimmerman’s right arm. After offseason surgery and a spring throwing program intended to improve his strength and mechanics, Zimmerman has lapsed into the same issues as last season, when he committed 12 throwing errors.

In the Nationals’ past six games, Zimmerman has committed four throwing errors, three of which led directly to losses. Those errors have led to seven unearned runs — more than 22 major league teams have yielded. The early throwing woes have left Zimmerman, the Nationals and rival evaluators wondering what the problem is and how best to fix it.

The ability to repeat a specific motion — whether it is throwing across the diamond or swinging the bat — lies at the core of baseball. It can be taken for granted until it can’t. A handful of players have dealt with the rare and puzzling loss of simple skills elemental to their job, pointing to a fragility about the game almost all players actively ignore.

All parties agree Zimmerman’s surgically repaired shoulder is healthy — “that’s why it’s so frustrating,” Zimmerman said. On Wednesday, General Manager Mike Rizzo expressed full confidence in Zimmerman and said it will simply take time for him to adjust to new mechanics in the wake of surgery and last season, when pain from an inflamed shoulder joint contorted his form.

“It’s getting a comfortable release point and arm slot — like a pitcher — that you can go to consistently without thinking about it,” Rizzo said. “It’s not unlike a pitcher’s mechanics or a hitter’s mechanics. You have to find the right slot and the right mechanics where it comes naturally, and that only comes with repetition.”

Manager Davey Johnson said before Wednesday’s game that, despite troubling results, Zimmerman’s mechanics are, “100 percent improved.” Rizzo acknowledged the recent struggles may be mental, because, “after you make a few throwing errors you start thinking about it. But he certainly is strong mentally and knows the game and understands what he’s trying to do. And it’s only a matter of time before he gets it.”

Figuring out the problem

Across the sport, there are varying views on how, if and when Zimmerman’s throwing will improve. Three scouts who are familiar with the Nationals, who were granted anonymity to speak freely about another team’s player, offered varying opinions on the severity of Zimmerman’s current struggles.

“He’s always been a mentally strong guy that’s made the big plays in big situations,” one National League scout said. “He’s been able to make adjustments and corrections in the past. I don’t think it’ll be any different this time. He’s such a good defensive player. I think you’re going to see his throws improve.”

Another NL evaluator watched Zimmerman make strong throws during the spring, causing him to upgrade his opinion of Zimmerman’s am strength. But over the past week, the scout believes old problems resurfaced and affected him mentally.

“It’s really starting to get in his head,” the scout said. “When I saw him in spring training, I thought it was getting better. I saw him make some great throws. Based on what I saw, I said, ‘The guy is healthy.’ If he’s healthy, why are his throws going all over the place? What could it be? . . .

“Maybe in three weeks, this is all resolved and he’s throwing the [stuffing] out of the ball. But until he starts doing it consistently, there’s going to be concerns. And there should be.”

Another scout from an American League team offered an even harsher take, suggesting Zimmerman may be past the point of repair.

“He’s got The Thing,” the AL scout said. “I’ve written it [in scouting reports] for two years. It just amazes me to watch him throw the baseball. He catches it. But, boy, if he’s got time to think about it, he’s in big trouble. He’s got the yips, The Thing, whatever you want to call it. There’s no doubt in my mind. . . . I don’t know if it’s fixable.”

Johnson dismissed the notion that Zimmerman’s mental outlook has spoiled his throws — “I don’t think it’s a mental problem right now,” Johnson said. “He’s fine and is only going to get better.” Johnson suggested Zimmerman’s errors had been magnified because pitchers had not squelched rallies following his errors.

“We’re not picking each other up,” Johnson said. “Good teams do that. It puts more focus on the guy making an error behind him, especially when he’s coming back from some surgery. I don’t have any concern.”

Finding a solution

With the season not yet three weeks old, the Nationals have no reason for immediate action. But a continued throwing slump could lead to more issues. The Nationals signed first baseman Adam LaRoche to a two-year, $25 million contract in January, which will make it difficult for Zimmerman to move across the diamond.

The roots of Zimmerman’s current throwing issues trace back to early 2011, when he and the Nationals decided his throwing motion, which had crept from overhand to nearly submarine-style, had contributed to the torn abdominal muscle he suffered eight games into the 2011 season. When he returned after surgery, Zimmerman overhauled his throwing mechanics, a change that made him more robotic.

Last season, shoulder issues exacerbated Zimmerman’s mechanics. He played through an inflamed shoulder joint with the help of cortisone. The injections shielded him from pain, but the inflammation and fraying inside his labrum and rotator cuff prevented his arm from moving how his brain expected it to. He lost all feel for his mechanics and later called it, “probably the first time I ever felt uncomfortable on a baseball field at any time.”

“Last year he was trying to find a place where he could throw comfortably,” Rizzo said. “Now he’s back up to where he belongs to play the position and he’s trying to find a consistency with that.”

Zimmerman’s throwing became a focus this spring, but he appeared to make strides as he advanced in a prescribed arm-strengthening program. Johnson said Zimmerman looked “more natural,” and Zimmerman did not make any throwing errors during Grapefruit League games or in the first nine games of the season.

“All of us have been throwing, for the most part, the same since we were 6, 7 years old,” LaRoche said. “It’s second nature. If I had to re-learn for three years in a row different ways, it takes time to get comfortable like that, your release point. I think that what’s been hard, so many changes and different things going on that he was forced to change. It’s going to take a minute.”

Wednesday afternoon, after stretching with the rest of his teammates, Zimmerman trotted out to right field in Marlins Park to play catch with LaRoche, at the front of the line of players warming up before the game. Zimmerman fired strikes consistently into LaRoche’s glove, even as he pulled further and further away into left field, just beyond the edge of the infield. The consistent and accurate throws looked little like the errant ones of the past week.

“Everything feels good,” Zimmerman had said the night before. “I long toss, my arm feels strong, everything’s good. It’s just a matter of me sticking with it and not mentally getting frustrated, just going out there and knowing that I can do that kind of stuff. I know I can do that.”